Washing Machine

Background

Mechanical washing machines appeared in the early 1800s, although they
were all hand-powered. Early models cleaned clothes by rubbing them, while
later models cleaned clothes by moving them through water. Steam-powered
commercial washers appeared in the 1850s, but home washing machines
remained entirely hand-powered until the early 1900s, when several
companies started making electric machines. The Automatic Electric Washer
Company and Hurley Machine Corporation both began selling electric washers
in 1907, while Maytag offered an electric wringer washer in 1911. In 1947,
Bendix offered the first fully automatic washing machine, and by 1953
spin-dry machines overtook the wringer types in popularity.

The last wringer washer manufactured in the United States was made in June
of 1990 at Speed Queen's plant in Ripon, Wisconsin. The major U.S.
manufacturers today are General Electric, Maytag (Montgomery Ward), Speed
Queen (Amana and Montgomery Ward), Whirlpool (Kenmore), and White
Consolidated (Frigidaire and Westinghouse).

Many models with many varying features are now available; however, with a
few exceptions, only the controls are different. The only difference
between the washer in your home and the top-load washers in the laundromat
is the ruggedness of construction.

The washing machine operates by a motor, which is connected to the
agitator through a unit called a transmission. The motor and transmission
are near the bottom of the machine, while the agitator extends up through
the middle of the machine. The transmission is similar to the transmission
in your
automobile
in that it changes the speed and direction of the agitator. In one
direction (agitate), the transmission changes the rotation of the agitator
and spin tub—the inside tub with small holes in it—into a
back-and-forth motion. When the motor is reversed by the controls (spin),
the transmission locks up and the agitator, transmission, and spin tub all
rotate as a unit. Without the transmission changing the speed or
direction, the unit uses centrifugal force to remove as much water from
the clothes as possible. The motor is also connected to a pump. When the
motor is moving in the spin direction, the pump removes the water from the
tub and discards it through the drain pipe.

Models designed for use in other countries offer different features. One
component required on all models sold in England (and possibly soon in the
rest of Europe) is called the lid lock. Normally when the lid is raised
the washer must stop for safety reasons. However, in England, when the
washer is operating the lid must be locked closed.

Raw Materials

Many parts of a washing machine are manufactured from sheet steel, usually
coated with zinc to improve rust resistance. The steel manufacturer
supplies the metal in a coil, which allows the material to be cut to size
with minimum waste or automatically fed into the forming process. On some
models made by Speed Queen, the spin tub is made of
stainless steel.
All other models use a steel (called enameling iron) designed for a
porcelain
coating. For the wash tub, which

Most sheet metal parts, including the body, are formed by a machine
that presses a piece of sheet metal between two halves of a mold
(die). Because metal in parts shaped by only one die tends to wrinkle,
crack, or tear, multiple dies are generally used to form each
component.
The tub sub-assembly is manufactured automatically. After being
rolled into a drum shape, the side is welded. The weld is then
smoothed out and the drum is placed on an expander, which stretches
the tub into its final shape. A bottom is then welded onto the drum,
and this weld is also smoothed.

isn't visible unless you open the machine cabinet, enameling iron
with a porcelain coating is generally used. Whirlpool is the exception,
using plastic instead of enameling iron for the outer wash tub.

Many other parts are plastic as well. Manufacturers receive raw plastic
from which they fabricate parts in pieces about the size of a small ant,
using them for machine components that do not bear weight and/or require
extremely good rust resistance. Such parts include the pump, the tub
guards (which prevent your clothes from being thrown out of the spin tub
into the wash tub or the cabinet area), and the agitator.

The transmission is generally made from cast aluminum, which arrives from
the manufacturer in ingots—20 pound slabs of aluminum. Scrap parts
are usually remelted and reused. Hoses, controls (timers, switches, etc.),
and motors are purchased in prefabricated form from other manufacturers.

The Manufacturing
Process

The manufacturing process is split into fabrication (making parts),
sub-assembly (putting parts together to make components), and assembly
(putting the components together to form the final product). The
fabrication process comprises several different procedures, each specific
to a particular type of raw material—sheet metal, plastic, or
aluminum. Once the constituent parts have been made, they are assembled;
major sub-assemblies, or components, include the transmission, the pump,
the spin and wash tubs, the balance ring, and the painted parts. Finally,
the sub-assemblies are put together inside the shell of the washer, which
is then complete.

Fabrication

1 Most sheet metal parts are formed by a machine called a press. This
name is quite descriptive, as the machine actually presses (or squeezes)
a piece of sheet metal between two halves of a mold called a die. The
metal will take the form of the space between the halves of the die.
Because metal in parts shaped by only one die tends to wrinkle, crack,
or tear, multiple dies are generally used to form each component. Where
possible, the metal is fed directly from a coil into the press. When
this is not possible, the metal is cut to length and manually (or, with
larger parts like the cabinet, automatically) placed into the die.

2 Plastic parts are formed in an injection molding machine, a metal mold
with one or more cavities in the shape of the desired part. After being
heated to its melting point, the plastic is forced into the mold under
high pressure. Next, water is passed through the mold to cool and
solidify the part. The mold is then opened and the part pushed out by
ejector pins. When you look at a plastic part, you often can see small
circles created by these pins.

3 Aluminum transmission parts are formed into a rough shape in a die
cast machine, which works much like an injection mold except that it
does not use pressure. The

Most of the key components—transmission, motor, broke
assembly—are housed below the agitator. The balance ring is a
weighted ring that keeps the washer from moving around during
operation.

molten metal is mechanically ladled into the mold and cooled. The
ensuing rough casting is then given its final shape by various machines
which drill holes, shave excess metal off critical surfaces, or cut
metal away from the part.

Sub-assemblies

4 The transmission is assembled manually by workers who bolt, snap, or
press (tight fit) several shafts and gears together. Workers then add a
metered amount of oil and bolt the unit together.

5 The pump is assembled automatically. Robots place the impeller and
seals in the cover and body, and seal the pump. Some manufacturers use
heat and others vibration (which generates heat) as a sealant.

6 The tub parts are made in presses, and the sub-assembly is
manufactured automatically. After being rolled into a drum shape, the
side is welded. The weld is then smoothed out and the drum is placed on
a unit called an
expander,
which stretches the tub into its final shape. A bottom is then welded
onto the drum, and this weld is also smoothed. If the tub is stainless
steel it is polished so it won't snag the clothes. Otherwise the
tub is dipped in a solution called a
ground coat
and heated to about 1600 degrees until this coating hardens. If the tub
will not be visible (the wash tub), the unit is done. If the tub will be
visible (the spin tub), a finish coat
is applied following the same procedure used with the ground coat; this
final coat gives the tub either a white or blue color.

7 The balance ring is a large weight that stabilizes the washer. Its
outside structure is plastic, with a ring of metal melted into the
plastic for strength. Cement is added and balanced precisely. This ring,
which weighs more than twenty pounds, keeps the machine from
"walking," or moving about, when it is in use.

8 Washing machine manufacturers use any one of several painting
processes. One manufacturer uses steel that has been prepainted by the
steel manufacturer. Although cheaper, this type of steel does not offer
the best rust protection because the cut edges are not painted. Other
companies treat their parts with various chemicals to clean and ready
them before applying
paint.
In some cases, the paint comes in a powder with a flour-like
consistency. Mixed with air and given an electrical charge, the powder
is sprayed on the part, which is hung from an overhead conveyor and
given an opposite charge so that it and the powder will attract one
another. After spraying, the conveyor moves the part into an oven that
melts the paint; when the part cools, the paint process is completed.

Assembly

9 This process begins with mounting the transmission on the balance
ring. The transmission is set on a bearing that is bolted on the wash
tub; the wash tub is sitting on a conveyor. Another bearing (the lower
bearing), the brake assembly, and the drive pulley are put on the end of
the transmission. Next, a pivoting mechanism called the
pivot dome
and legs are bolted on the assembly to hold all the pieces together.

10 Using a hydraulically operated mechanism, workers then lift this
assembly, called the
module,
onto the washer base. Springs are added to hold module and base
together. A seal is added, the spin tub is bolted to the transmission
inside of the wash tub, and its plastic covers are snapped into place. A
plastic hub, which attaches the agitator to the transmission, is bolted
onto the output end of the transmission shaft. Then the agitator is
snapped onto the hub.

11 The pump and a mounting bracket are now bolted onto the motor, which
is then fitted with a shield to protect against potential leaks. This
assembly is bolted to the base of the washing machine and connected to
the transmission module with a belt and hoses.

12 Next, the lid hinges are attached to the lid and the top. The top of
the washer is bolted to the cabinet with a hinge for easy maintenance. A
mixing valve to control the mixture of hot and cold is bolted to the
back of the cabinet. The graphics panel, which provides words and
pictures to explain the controls, is mounted on the control panel; the
controls themselves are attached from the back. The wiring, connected as
one unit, is called a
harness.
The harness is clipped to the control connectors at one end, and the
other end is passed through a hole in the top to be mounted to the
motor. Because of its large size and weight, the cabinet assembly is
then placed in the washer by a robot.

13 The cabinet is bolted to the base, and the controls are snapped
together with the mating connectors on the module and motor. The drain
hose is pulled through the cabinet and a part called the
gooseneck
is added. This part is what gives the hose its hook shape so that it
will fasten into the drain. After being tested, the front panel is
bolted on, and a packet of information and accessories is added.

14 The finished unit is crated automatically. A machine opens the
cardboard box, which was flat for shipment, and drops it over the
washer. The top and bottom flaps are simultaneously folded over and
glued. Then the machine applies pressure on the top and bottom of the
crate to make sure the glue sets properly. After the glue has set, the
machine puts a banding strap around the top of the crate to add strength
for lift truck transportation (the units are carried from the top to
reduce the risk of damage).

Quality Control

All parts purchased from outside manufacturers are spot checked before
use, and most sub-assemblies are checked as well. For instance, all
transmissions are automatically tested for operation, noise, and
vibration. All
pumps are leak-tested using air, automatically if their assembly was
automated and manually if it was manual. All painted parts are visually
inspected for defects. Daily samples are put in detergent, bleach, and
steam baths for corrosion testing. Once it has been completely assembled,
the machine is filled with water and tested for noise, vibration, and
visual defects, as well as properly functional controls and mechanisms.
After packaging, some units are put through severe tests to simulate the
transportation conditions to test the cartoning process.

Byproducts/Waste

Leftover scraps of sheet metal are sold to metal recycling centers, and
leftover aluminum is remelted for use. The leftover plastic is ground into
small chunks and reused on non-visible parts because the color cannot be
kept consistent. The unused paint (in powder form) is reclaimed and reused
automatically. The chemicals from processes such as paint are reacted into
forms of harmless waste and disposed of safely.

The Future

As motors become less expensive and more durable, it will become
economical to offer washing machines driven directly by motors instead of
by belts, making the washers more versatile and less noisy. Another likely
trend will be the gradual displacement of top-load washers by front-load
washers, which, because they require less water, satisfy government
restrictions on water use. In Japan, a washer is being tested that cleans
with bubbles rather than with an agitator. Using a computer, this machine
"senses" how soiled each load of clothing is and then
generates the bubble activity necessary to remove that amount of dirt.
This is called "fuzzy logic" because it imitates human logic
more closely than normal computers. If successful, these machines will
become available elsewhere. Further in the future people may use washers
that clean using ultrasonics—sound waves that, vibrating at
frequencies of more than

Although at present most home washing machines in the United States
are top-loading, these will likely be gradually displaced by
front-load washers. Because they require less water, front-load
washers satisfy government restrictions on water use. Also, in Japan a
washer is being tested that cleans with bubbles rather than with an
agitator. Using a computer, this machine "senses" how
soiled each load of clothing is and then generates the bubble acfivity
necessary to remove that amount of dirt.